In view of vivid hue, staining of white area and fastness, reactive dyes are frequently used for dyeing (printing, in particular) of cellulose fibers. Among them, reactive dyes having monochlorotriazino group as the reactive group are preferably used because the color pastes have excellent stability on standing. More specifically, as these reactive dyes, C. I. Reactive Orange 99 as yellow dyes, C. I. Reactive Red 3:1 as red dyes and C. I. Reactive Blue 49 and C. I. Reactive Blue 5 as blue dyes are exemplified.
The reactive dyes for use in printing of cellulose fibers are required to have the following quality properties.
1. Having good dyeing reproducibility, owing to the less dependency on the conditions for intermediate drying after color pastes are printed on the fibers. This property is dependent upon the affinity of a dye to cellulose fibers; when the affinity of a dye is too low, dyeing reproducibility is poor because the dependency on the conditions for intermediate drying is elevated (when a relatively long time is needed until the dyed fiber is dried up, the migration of the dye to the back face of the resulting printed cloth is so great that the depth of shade on the surface of the printed cloth is reduced). Such dye is poor in terms of reproducibility of a color dyed by combined dyeing of yellow dyes, red dyes or blue dyes between laboratory tests and field processing.
2. Having good dyeing reproducibility owing to the less dependency of reactive dyes on the steaming conditions (steaming duration, in particular) at a reacting and fixing process. This property is dependent upon the dye reactivity; it is required that reactive dyes have such appropriate reactivity that stable reacting and fixing (high depth of shade) can be attained even when the steaming conditions (steaming duration) vary. The property has a significant influence on the dyeing reproducibility at field.
3. Reducing in staining of white area (area with no color pastes printed thereon) and being able to obtain high-quality print by printing processing.
4. Having excellent fastness (especially light fastness and chlorine fastness) in a printed product and the long color life in the printed product.
From the standpoint of the quality properties required for such dyes for printing, known blue dyes have serious drawbacks. Anthraquinone blue dyes such as C. I. Reactive Blue 49 and C. I. Reactive Blue 5 are currently used frequently, but these dyes exhibit such high dependency on the conditions for intermediate drying as described above in 1 that the reproducibility between the result dyed at laboratory tests pand the result dyed at fields is poor, leading to serious deterioration of the productivity. Additionally, these dyes are seriously poor in terms of the fastness, particularly chlorine fastness as described above in 4, so the color life of the resulting products is short.
JP-B-Hei5-21945 proposes a formazan blue dye as a means for improving the chlorine fastness, but the formazan compound described therein has a number of drawbacks described below: t he compound is highly dependent on the steaming duration as described above in 2, leading to poor dyeing reproducibility at fields, with the resultant poor productivity alike; furthermore, the compound is poor in terms of reducing of the staining of white area as described above in 3, so the resulting products dyed by printing are of deteriorated quality.
It has been highly desired to develop a blue dye capable of satisfying all of the quality properties described in 1 to 4 as required for reactive dyes to dye cellulose fibers, namely a blue dye with low dependency on the conditions for intermediate drying and low dependency on the steaming conditions and with good dyeing reproducibility, satisfactory reduced staining of white area and sufficient chlorine fastness, and with additional abilities enabling the improvement of the productivity of printing process and the preparation of high-quality products with long lives.